"Weighed down by debt, and reeling from the latest downgrading of their country's credit status, Portugal's finance ministry has secured the co-operation of football's highest-paid player in an audacious bid to draw the nation back from the brink of economic collapse.

In a move which some observers claimed "will lead to the destruction of the World Cup", Cristiano Ronaldo has agreed to "act like a patriot" and be sold to neighbouring Spain for €160m.

Last week, Prime Minister José Sócrates resigned after his government's latest austerity package was rejected by parliament. His move followed the downgrading of his country's credit rating to the category above "junk". While Ronaldo's fee, though double the current record (paid by Real Madrid to Manchester United for Ronaldo's club affiliation in 2009) barely dents the €12bn Portugal owes, Mr Socrates, now caretaker premier, believes that the international bond markets will take it as a symbol of Portugal's determination to tackle the crisis, and respond accordingly.

Although no footballer has ever previously been "transferred" between countries, there is extensive precedent for changing nationality, especially in Spain. Two of the greats, Alfredo di Stéfano and Ferenc Puskás, played for the Spanish national team after representing other countries and then taking Spanish citizenship. Di Stéfano – who is still involved at Real Madrid and is thought to have influenced Ronaldo's decision – had played for Argentina and Colombia. Puskás even played in the 1954 World Cup final for Hungary but went into exile after the crushing of the 1956 revolution. As recently as Spain's 2008 European Championship triumph, Marcos Senna, Brazilian by birth and parentage, was a key player.

Senna, however, had not played for Brazil. Since Puskás' day, Fifa, the world governing body, has tightened its rules. Once a player has played a competitive international for one country – at any age group – he cannot switch allegiance unless he had dual nationality at the time, and was educated in the second country. Mikael Arteta, Everton's Spanish midfielder, abandoned an attempt to play for England because he had played competitively for Spain under-21s. But Fifa's secretive executive committee is expected to meet today, in extraordinary session, to adapt its statutes to permit such moves in circumstances where both governments agree.

"It's insane," said a spokesman for the Bruges-based Keep Football Pure organisation. "Those idiot administrators have not thought it through, as usual. There's now nothing to stop Qatar buying a World XI. It'll destroy the World Cup, it will turn it into another Champions League – only worse."

Opinion is divided in Portugal. While many see Ronaldo's agreement to the move as the "ultimate patriotic gesture" others regard the transfer as a "surrender". Paolo Fril, professor of political economics at Lisbon University, told The Independent: "We were ruled by a Spanish king for 60 years [1580-1640] and had to go to war to win back our independence. This is not about Spain saving us –they are restoring the Iberian Union by the back door."

There are doubts in Spain, too. The issue is not naturalising Ronaldo, but whether he is needed. Spain are the current world and European champions, with a style of play that relies more on passing than the soloist skills for which Ronaldo is known. "If we are going to buy foreigners we should buy Lionel Messi [Barcelona's Argentinian star]," said one fan.

But if Ronaldo is unappreciated in Spain, his skills may be in demand elsewhere. Late last night, reports suggested that David Cameron was preparing a counter-offer, of £200m, to persuade Ronaldo to play for England. "The Premier League is where Ronaldo became a star," said the Prime Minister, "so it is only right and proper he should play for England." He added that Vince Cable had proposed a "Ferrari tax" to pay for it, though Ronaldo himself would be given exemption."